i have been masking for 50 years

I've found found that unmasking is basically not only about letting others see your autistic traits, but it's about me myself willing to be vulnerable in front of others.  Having to explain myself a bit but generally, unless people are arses, they are more open to expressed vulnerability these days. It's part of the zeitgeist I'd say atm

I realized that in December. Changing my posture to look relaxed, mimicking people, making eye contact to seem interested, monitoring every social situation. feeling exhausted after spending time with people. 

This community is very understanding, friendly and supportive so you've come to the right place

Many here know what you speak of.  Welcome.

Perhaps small steps for now to get used to feeling confident

Welcome, my friend. 

It's a jungle, out there. Never go without a guide.